The present invention relates to the fields of soldering and cathode ray tube manufacture. More specifically, the present invention relates to the use of soldering to create electrodes on the anti-reflective film of a cathode ray tube. The present invention provides a pressure gauge or monitor for a soldering iron so that the pressure applied to the iron when forming a solder electrode on an anti-reflective film of a cathode ray tube can be monitored and kept consistent from unit to unit within optimal parameters.
Cathode ray tubes (xe2x80x9cCRTsxe2x80x9d) are used in most television sets and computer and video monitors. A typical CRT is illustrated in FIG. 1. The CRT (100) is a glass tube with a bottle-like shape in which a relatively flat bottom portion (101) narrows into an elongated neck portion (102). The relatively flat portion (101) of the CRT (100) is the viewing surface and becomes the screen on which the display of the television set or monitor is generated when the CRT is incorporated therein.
An electro-luminescent material, such as phosphorus, that emits light when struck by an electron beam, is coated over the interior of the screen portion (101) of the CRT (100). An electron gun is then installed in the neck (102) of the CRT (100). A stream of electrons emitted from the electron gun is scanned over the electro-luminescent layer and turned on and off during the scanning to cause the electro-luminescent layer to glow in certain places and not others. In very simple terms, this is how an image is generated on the screen of a television or video monitor.
A yoke (not shown) is provided around the neck (102) of the CRT (100). This yoke produces a changing magnetic field through which the electron beam from the electron gun passes. The electron beam is deflected by the magnetic field of the yoke. Consequently, by varying the magnetic field created by the yoke in a precise cycle, the electron beam can be scanned, line-by-line, over the entire surface of the screen to generate video images thereon.
A cathode ray tube is generally constructed in the following matter. The neck (102) or funnel portion of the CRT (100) is formed open at both ends. Then the relatively flat bottom, or display portion (101) is sealed to the large end of the funnel and the electron gun is installed in the narrow end or neck of the funnel. The display portion (101) is sealed to the funnel (102) using frit. Frit is a glass paste that can be cured or hardened. Frit, in paste form, is applied around the large end of the funnel (102) between the funnel (102) and the display portion (101). The frit is then cured or hardened to form a frit seal between the funnel (102) and the display portion (101).
After the frit is sealed, the tube (100) is evacuated and a strong vacuum is maintained inside the tube (100) throughout its life. Because of the strong vacuum inside the tube (100), there is a minimal risk that the tube (100) could implode. This risk is, of course, heightened if the tube (100) is damaged or mishandled. In the event of an implosion, a major concern would be flying glass shrapnel produced by the implosion.
To minimize the risk of both an implosion and a resulting spray of shrapnel, a metal band (103) is wrapped around the cathode ray tube (100) over the frit seal. This band (103) is called a reinforcement or heat-shrinkage (xe2x80x9cHSxe2x80x9d) band.
An anti-reflective film (104) is also applied over the viewing surface of the screen portion (101). This anti-reflective film (104) minimizes the reflection of external light from the screen (101) of the cathode ray tube (100). Such reflection degrades the quality of the image that can be displayed on the screen (101) of the tube (100).
The anti-reflective film (104) is in electrical contact with solder electrodes (105) that are formed on the film (104). During the operation of the cathode ray tube (100) as a television or video monitor, the anti-reflective film (104) is electrically grounded through the solder electrodes (105). This grounding prevents a build-up of an electric charge on the anti-reflective film (104). Such an accumulated charge can damage the anti-reflective film (104).
The solder electrodes (105) are electrically connected to the HS band (103) by a piece of conductive tape (106), as shown in FIG. 1. This conductive tape (106) provides an electrical path from the solder electrode (105) into the HS band (103) for purposes of grounding the anti-reflective film (104) of the surface of the screen (101).
The solder electrodes (105) are typically formed by a technician operating a solder iron. During the application of solder to the anti-reflective film (104) to form the solder electrodes (105), the technician applies pressure to the soldering iron to cause the solder to properly adhere to the anti-reflective film (104). If the technician applies too little or too much pressure, the quality of the solder bead and the resulting solder electrode (105) will be compromised.
If the solder electrode (105) is not properly formed and fails to adequately ground the anti-reflective film (104), i.e., release accumulated charge from the anti-reflective film (104), several negative consequences can result. First, the anti-reflective film (104) can be damaged. Secondly, the end user of the CRT is at risk of being shocked if he or she touches or comes too close to the screen (101) when a large accumulated charge is present and looking for a path to ground.
Consequently, there is a need in the art for a method and apparatus that helps ensure that the solder electrodes on the anti-reflective film of a cathode ray tube are properly formed. More specifically, there is a need in the art for a method and apparatus that monitors or controls the pressure applied to a solder bead when a solder electrode is being formed so as to keep that pressure consistent between units and within optimal parameters.
The present invention meets the above-described needs and others. Specifically, the present invention provides a method and apparatus that helps ensure that the solder electrodes on the anti-reflective film of a cathode ray tube are properly formed by that monitoring or controlling the pressure applied to a solder bead when a solder electrode is being formed so as to keep that pressure consistent between units and within optimal parameters.
Additional advantages and novel features of the invention will be set forth in the description which follows or may be learned by those skilled in the art through reading these materials or practicing the invention. The advantages of the invention may be achieved through the means recited in the attached claims.
The present invention may be embodied and described as a soldering iron in combination with a pressure monitor. This novel device preferably includes a soldering iron having a soldering tip; and a pressure monitor mounted on the soldering iron, the pressure monitor monitoring the pressure with which the soldering iron is applied.
In a preferred embodiment, the pressure monitor includes a spring that is compressed in correspondence with the pressure of the soldering iron. The spring is preferably a coil spring surrounding the soldering tip.
A pressure platform is also preferably provided on the end of the spring. The pressure platform preferably provides roller bearings or some other member to prevent the spring from scratching the work-piece.
In one preferred embodiment, the pressure monitor includes a gauge with a needle that is deflected along a numeric scale in correspondence with compression of the spring. Alternatively, circuitry in the soldering iron may electronically produce a value indicative of the pressure in correspondence with compression of the spring. A display screen can then be included on the soldering iron for displaying the pressure value in numeric form.
In an automated embodiment, a robotic arm is used to position and apply the soldering iron to a work-piece. The robotic arm is controlled with a robotic arm controller.
This embodiment includes circuitry in the soldering iron to electronically produce a value indicative of the pressure in correspondence with compression of the spring. The pressure value produced by the circuitry is transmitted to the robotic arm controller, and the robotic arm controller controls the robotic arm and soldering iron in accordance with the pressure value.
The present invention also encompasses the methods of making and using the system described above. In particular, the soldering iron and pressure monitoring system of the present invention can be profitably used in forming solder electrodes on the anti-reflective film of a cathode ray tube. Specifically, the present invention encompasses a method of forming a solder electrode on an anti-reflective film of a cathode ray tube by monitoring a pressure applied with a soldering iron that is forming the solder electrode; and maintaining the pressure within a pre-determined optimal range.
The method of the present invention is preferably performed by compressing a spring on the soldering iron in correspondence with the pressure applied. As described above, this compression may be used for deflecting the needle of a pressure gauge along a numeric scale in correspondence with the compression of the spring. Alternatively, this compression may be used for electronically producing a value indicative of the pressure in correspondence with the compression of the spring. This pressure value may then be displayed in numeric form.
Finally, the method of the present invention may be applied to an automated process including positioning and applying the soldering iron to a work-piece with a robotic arm; controlling the robotic arm with a robotic arm controller; transmitting the pressure value to the robotic arm controller; and controlling the robotic arm and soldering iron with the robotic arm controller in accordance with the pressure value.